All posts by mathconfidence

brain puzzler

April 2018 Brain Puzzler Solution

Leave a comment

Q: How many 6 digit numbers are there whose digits sum to 51?

A: 56.

There are 3 possible sets of 6 numbers: 999996 where the 6 can be the 1st, 2nd, 3rd, 4th, 5th, 6th place values making 6 6 digit numbers

3 9s and 3 8s which is the same probability as 3 boys and 3 girls with 6 children 3C6 = 20 6 digit numbers

and 4 9s with an 8 and a 7 with 30 possibilities
789999
798999
799899
799989
799998
879999
897999
899799
899979
899997
978999
979899
979989
979998
987999
989799
989979
989997
997899
997989
997998
998799
998979
998997
999789
999798
999879
999897
999978
999987

 

 

 

credit to Julia Robinson Mathematics Festival

Common Core Algebra I, Regents

Get the Math and Points! Domain and Range (Which comes 1st in the alphabet?)

Leave a comment

CC Alg I Jan 2018 12
Domain means x values and Range means y. 
D comes before R in the alphabet and x is before y.
This problem gives us x values so use them to find y.
f(x) = 2x^2 – 8
f(-2) = 2(-2)^2 – 8 = 2(4) – 8 = 0  (This narrows it down to answers (3) or (4)!)
f(3) = 2(3)^2 – 8 = 2(9) – 8 = 10 (This makes the answer jump out at ya!)
f(5) = 2(5)^2 – 8 = 2(25) – 8 = 42
Can also use the table from the TI-84 :)
CC Alg I Jan 18 12

Common Core Algebra I, Regents

Get the Math & the Points! Jan 2018 CC Alg I Regents #6

Leave a comment


Look for the point that does not make the equation true.
This is a very accessible question as all the x values in the choices are negative integers (-4, -3, -2, and -1) and will easily be found on the table.
When x = -4, y = -60 check
When x = -3, y = -24 check
When x = -2, y = -6 check
Um, when x = -1…
Most, if not all students, can build understanding of Math and critically think while gaining points to pass the Regents!  This question from January 2018 asks the student to notice the word not and to find the point that does not belong.

2 points :)